Effects of bile salt hydrophobicity on crystallization of cholesterol in model bile

Precipitation of cholesterol crystals is an essential step in gallstone formation. In the present study we found much faster and more extensive precipitation of various cholesterol crystal shapes in whole model biles containing the hydrophobic bile salt taurodeoxycholate than in biles containing the relatively hydrophilic taurocholate. Addition of taurodeoxycholate to isolated cholesterol–phospholipid vesicles also induced more crystallization than taurocholate. Crystallization behaviour in whole model biles and in vesicles after addition of corresponding bile salts was very similar. The very hydrophilic bile salts tauroursodeoxycholate and taurohyodeoxycholate never induced crystallization from vesicles, and crystallization in corresponding whole model biles did not occur. These bile salts also reduced crystallization dose dependently after addition of taurodeoxycholate to vesicles. Ultracentrifugation experiments suggested a higher vesicular cholesterol–phospholipid ratio for whole model biles containing more hydrophobic bile salts. These findings indicate that bile salt hydrophobicity influences shape of cholesterol crystals and extent of crystallization, possibly by modulating the vesicular cholesterol–phospholipid ratio.     

Biliary lipid composition in patients with cholesterol and pigment gallstones and gallstone-free subjects: deoxycholic acid does not contribute to formation of cholesterol gallstones

BACKGROUND: Four main disturbances have been attributed to cholesterol gallstone disease: hypersecretion of cholesterol from the liver with cholesterol supersaturation in bile; disturbed motility with defective absorption and secretion by the gallbladder; increased crystallisation of cholesterol in the gallbladder bile; and slow intestinal transit with increased amount of deoxycholic acid in the bile acid pool. We aimed to evaluate the biliary lipid composition in a large series of gallstone patients, with emphasis on the amount of deoxycholic acid and with respect to number of stones, compared to gallstone free subjects. MATERIALS AND METHODS: Bile was sampled during operations through puncture of the gallbladder from 145 cholesterol gallstone patients, 23 patients with pigment stones and 87 gallstone free patients undergoing cholecystectomy. Biliary lipid composition, cholesterol saturation, bile acid composition, nucleation time and cholesterol crystals were analysed. RESULTS: The patients with cholesterol gallstones showed higher molar percentage of cholesterol, lower total biliary lipid concentration, higher cholesterol saturation, shorter nucleation time and higher proportion of crystals in bile than the other groups. The nucleation time was significantly shorter in multiple cholesterol gallstone patients, but this was not due to higher cholesterol saturation. Male cholesterol gallstone patients showed higher cholesterol levels, lower total biliary lipid concentration, and higher cholesterol saturation in bile than female patients. There was no difference in biliary content of deoxycholic acid, but significantly lower content of cholic acid in gallstone patients compared to gallstone free patients. CONCLUSIONS: We conclude that deoxycholic acid does not contribute to gallstone formation in cholesterol gallstone patients. The short nucleation time in patients with multiple cholesterol stones is not due to higher cholesterol saturation.     

Cholesterol saturation rather than phospholipid/bile salt ratio or protein content affects crystallization sequences in human gallbladder bile

BACKGROUND: In model biles, cholesterol crystallization (an important factor in gallstone formation) mainly depends on phospholipid/bile salt ratios with characteristic sequences of plate-like (monohydrate) vs. non-plate-like (presumed anhydrous: arcs, needles, tubules, spirals) cholesterol crystals. We now investigate whether the same phenomenon occurs in human bile. METHODS: Appearances of plate-like and non-plate-like cholesterol crystals were determined in filtered bile of 80 cholesterol gallstone patients, and related to biliary lipid and pro-nucleating protein composition. RESULTS: Non-plate-like crystals appeared before plate-like crystals in 9 biles, on the same day in 24 biles, and after plate-like crystals in 31 biles. In 16 biles only plate-like crystals were observed. Crystal sequences did not depend on biliary lipid or protein composition. Cholesterol saturation indexes were higher in biles with than without non-plate-like crystals (150 +/- 6 vs. 125 +/- 12, P = 0.02). In contrast, phospholipid/(bile salt + phospholipid) ratios, bile salt species, phospholipid classes, concentrations of mucin, IgG, IgM, IgA, haptoglobin and alpha-1 acid glycoprotein did not differ. CONCLUSIONS: Cholesterol crystallization sequences in human bile depend on cholesterol saturation index rather than on phospholipid/bile salt ratio.     

Bile acid and phospholipid fatty acid composition in bile of patients with cholesterol and pigment gallstones.

It has been previously reported that patients with cholesterol gallstones have increased biliary deoxycholate and arachidonate content as compared with normal subjects without gallstones. Increased biliary deoxycholate and arachidonate content might be a primary factor in the pathogenesis of cholesterol gallstones or merely an epiphenomenon due to the presence of gallstones. We therefore compared biliary bile acid composition in 46 patients with cholesterol gallstones and 22 patients with pigment stones. In addition, biliary phospholipid fatty acid composition was determined in 44 of these patients (30 cholesterol and 14 pigment stone patients). No significant differences were detected. In particular, the percentage deoxycholic acid (mean +/- SD: 20.3 +/- 8.8% and 21.5 +/- 10.9% respectively) and the percentage arachidonic acid (4.4 +/- 2.0% and 4.5 +/- 2.2%, respectively) were very similar. A significant correlation between age and biliary cholesterol saturation index was found only for the group of patients with pigment stones (R = 0.52, p less than 0.02). In conclusion, the present study does not support a primary role for increased biliary deoxycholic acid or arachidonic acid in the pathogenesis of cholesterol gallstones.     

Free fatty acid concentrations in gallbladder bile collected from Chilean patients with gallstones

OBJECTIVES: To evaluate the association between gallstones and biliary free fatty acids (FFAs) as the first attempt to clarify whether biliary FFAs relate to developing gallbladder cancer (GBC) in Chile, which has the highest mortality rate in the world. DESIGN AND METHODS: Gallbladder bile from 21 male and 129 female patients with gallstones from Santiago was collected, and their FFAs were measured. The results were compared with those observed in a similar previous study performed in Niigata and Kochi Prefectures which showed the highest and lowest mortality rates, respectively, for GBC in Japan. RESULTS: Palmitoleic and linolenic acids compositions in Santiago patients were significantly lower than those in Niigata and Kochi patients, though these compositions in Niigata patients were significantly lower than those in Kochi patients. The levels of these FFAs compositions decreased in the order of Kochi, Niigata, and Santiago patients. CONCLUSIONS: Decreased biliary FFAs compositions may relate to developing gallstones and subsequently GBC.     

Effects of dietary cholesterol on cholesterol and bile acid homeostasis in patients with cholesterol gallstones.

We examined changes in cholesterol and bile acid metabolism produced by dietary cholesterol in gallstone subjects and matched controls. Healthy women were recruited and, after confirming the presence or absence of radiolucent gallstones, they were studied on regular diets and again on the same diet supplemented with five eggs daily for 15-18 d. Studies included plasma lipids, lipoproteins and apolipoproteins, dietary records, cholesterol absorption, cholesterol synthesis, plasma clearance of chylomicron remnants, biliary lipid composition, and secretion and bile acid kinetics. On low cholesterol, gallstone subjects absorbed a slightly lower fraction of dietary cholesterol, synthesized more cholesterol, and had smaller bile acid pools and faster fractional turnover rate (FTR) of bile acids. On high cholesterol, the fraction of cholesterol absorbed decreased in both groups and cholesterol synthesis decreased, especially in the gallstone group. Biliary cholesterol secretion increased in the gallstone group only. FTR of bile acids did not change in either group. Bile acid synthesis and pool tended to increase (P = NS) in the controls, but in gallstone subjects, synthesis and pool size decreased. We concluded that in gallstone subjects cholesterol and bile acid homeostasis is significantly altered, and that increasing dietary cholesterol increases biliary cholesterol secretion and decreases bile acid synthesis and pool, changes associated with cholesterol gallstone formation.     

Effect of drugs on cholesterol crystallization in an artificial bile model and relation of this effect to drug binding to albumin

Substances that can affect the crystallization of cholesterol from human bile and consequently the gallstone formation have been given considerable attention. We improved the model system for testing cholesterol crystallization-affecting activity (promoting or inhibiting) of substances and used it for some drugs that are excreted into bile. Besides other factors natural lipid-protein complexes isolated from the native human bile have been shown to be responsible for nucleation and fast crystal growth in cholesterol supersaturated model bile. Artificial lipid-protein complex of taurolithocholate, human serum albumin and Ca2+ (TLTC-HSA-Ca2+) exhibited a lower crystallization activity than both the artificial lipid-protein complexes of taurodeoxycholate, human serum albumin and Ca2+ and the lipid-protein complex isolated from native human bile. The model bile supplemented with this artificial lipid-protein complex (TLTC-HSA-Ca2+) formed a convenient system for testing of various substances (drugs) for their crystallization-affecting activity. From the 20 tested drugs, which could occur at least in small amounts in human bile, the highest crystallization-promoting activity was found for complexes with ampicillin, butorphanol and colchicine. Complexes with tetracycline, thioridazine and doxycycline were the strongest inhibitors. The drugs, which had some effect on cholesterol crystallization, affected somehow the artificial lipid-albumin complex by displacing its components. Interactions of different drugs with HSA and its artificial complexes with the conjugated bile salt and Ca2+ ions were followed by absorption spectroscopy to observe displacement interactions. On the basis of these experiments we could classify drugs into four groups which differ by their effects on spectral characteristics of complexes.     

Chronic administration of chenodeoxycholic acid increases cholesterol saturation in bile in the dog

Six dogs were given chenodeoxycholic acid, 200 mg/day for 15 days; gallbladder and hepatic bile samples were taken and biliary bile acids, phospholipids and cholesterol were compared to those of fourteen control dogs. It was found that: (1) the cholesterol saturation index of gallbladder bile was higher in treated dogs (0.12 +/- 0.06; m +/- SD) than in controls (0.07 +/- 0.01; P less than 0.05); the proportion of chenodeoxycholic acid in gallbladder bile was higher in treated dogs (27.8 +/- 12.5%) than in controls (4.5 +/- 1.9%; P less than 0.01); (2) in hepatic bile, the saturation index and proportion of chenodeoxycholic acid were significantly higher in treated dogs (respectively 0.13 +/- 0.03 and 21.6 +/- 8.8%) than in control dogs (respectively 0.07 +/- 0.01; P less than 0.01 and 4.6 +/- 2.2%; P less than 0.01). In the dog, chronic administration of chenodeoxycholic acid increases cholesterol saturation in bile. It is concluded that the difference of effect of chenodeoxycholic acid in man and in the dog is not related to the duration of administration, but to a species difference.     

Biliary lipid excretion in patients with pigment gallstones. A comparison with cholesterol gallstone patients

Pigment gallstone patients are believed to have normal biliary lipid excretion. In order to measure this and to better understand cholesterol gallstone formation, the kinetics of biliary lipid excretion were studied in three patients who had been cholecystectomized for pigment gallstones and the results compared to those previously obtained in patients cholecystectomized for cholesterol gallstone. Pigment-stone patients had hyperbolic relationships between cholesterol and phospholipid outputs and bile salt output which were similar to those seen in cholesterol-stone patients. However, pigment-stone patients excreted more cholesterol and phospholipid at high bile salt output but approached those levels more gradually than cholesterol-stone patients. As a result, pigment-stone patients produced bile undersaturated with cholesterol at a lower bile salt output than cholesterol-stone patients, and thus they would be less likely to produce supersaturated bile during low bile salt output such as that occurring during an overnight fast. The data suggest that cholesterol-stone patients, in addition to excreting more cholesterol and less bile salts than normals, have a defect in the rate of lipid output in response to decreasing bile salt output.     

Clofibrate treatment and bile cholesterol saturation: short-term and long-term effects and influence of combination with chenodeoxycholic acid

Abstract . In order to determine whether the clofibrate-induced increase in bile cholesterol saturation is transitory, duodenal bile samples were analysed from sixteen hyperlipoproteinaemic patients before and after 6 months to 2 years treatment with clofibrate, 2 g daily. Standardized dietary and weight conditions were obtained. In all but two subjects cholesterol saturation remained elevated (150 ± 7%, mean ± SEM) compared to pretreatment values (112 ± 6%, P < 0.01).
In nine of the patients, duodenal bile was obtained also after 6 weeks of treatment. Although two patients with increased saturation at 6 weeks displayed a return to basal values at 2 years, the majority showed no consistent changes between these two occasions.
Addition of chenodeoxycholic acid to clofibrate medication led to a normalization of cholesterol saturation (from 145 ± 9 to 89 ± 18%, P < 0.01) in eight out of nine patients studied. The serum levels of total cholesterol and triglycerides, very low density lipopro-tein and high density lipoprotein cholesterol were not significantly changed. However, the low density lipoprotein (LDL) cholesterol concentration was increased by 15–20% (from 4.8 ±0.3 to 5.7 ± 0.4 mmol/l, P <0.01).
It is concluded that clofibrate induces changes in biliary lipid composition which are consistent over at least 2 years of treatment. Possible measures to avoid these effects must therefore also be taken over a prolonged time. Chenodeoxycholic acid prevents the lithogenic effect of clofibrate but it cannot presently be recommended as an adjunct to clofibrate treatment since it simultaneously causes a rise in the serum concentration of LDL-cholesterol.     

The formation of abnormal bile and cholesterol gallstones from dietary cholesterol in the prairie dog

To study the pathogenesis of cholesterol gallstones, we fed 24 adult male prairie dogs a high cholesterol, egg yolk diet. 13 control animals received a cholesterol-free diet. All animals fed the egg yolk diet formed multiple gallstones in 2-6 months' time. These stones contained cholesterol, 77+/-14% by dry weight. No stones ocurred in the control group.The egg yolk-fed animals developed bile of altered chemical composition. The cholesterol concentration of hepatic and gallbladder bile increased significantly. The molar ratios of bile acid/cholesterol and phospholipid/cholesterol decreased in hepatic and gallbladder bile. The predominant bile acid shifted from cholic acid, 78% of the total bile acids, to chenodeoxycholic acid, 60% of the total. In common bile duct cannulated animals the high cholesterol diet produced increased secretion of cholesterol by the liver and increased bile flow.In animals fed the egg yolk diet for 2 months, cholesterol-4-(14)C was included in the daily diet for the next 4 months to establish an isotopic steady state. At autopsy the mean specific activity of cholesterol was similar in serum, liver, hepatic bile, gallbladder bile, and gallstones. Thus the cholesterol of gallstones apparently equilibrated constantly throughout the study and was not sequestrated as a static pool.The high cholesterol, egg yolk diet caused the secretion of an "abnormal bile" which led to precipitation of cholesterol from micellar solution. The increased bile cholesterol relative to bile acid and phospholipid favored stone formation. This dietary induction of cholesterol gallstones provided a unique animal model, in part but not completely analogous to human cholelithiasis.     

Effects of combined treatment with pravastatin and ursodeoxycholic acid on hepatic cholesterol metabolism

BACKGROUND: Treatment with ursodeoxycholic acid and also, to some degree, statins reduces cholesterol saturation of bile. The present study aimed [1] to study the effects of combined treatment with ursodeoxycholic acid and pravastatin on hepatic cholesterol metabolism and [2] to evaluate if the addition of pravastatin to ursodeoxycholic acid treatment has beneficial effects on the lipid composition of gallbladder bile in gallstone patients. MATERIALS AND METHODS: Nineteen patients with cholesterol gallstones were subjected to combined treatment with ursodeoxycholic acid (500 mg bid) and pravastatin (20 mg bid) for three weeks before cholecystectomy. Eleven patients received ursodeoxycholic acid only and 20 untreated gallstone patients served as controls. Gallbladder bile was collected, and for both the patients receiving combined treatment and the controls a liver biopsy was also obtained peroperatively. RESULTS: The cholesterol saturation of bile averaged 59% in the patients on combined treatment, 60% in the ursodeoxycholic acid-treated patients, and 130% in the untreated controls. In the patients receiving ursodeoxycholic acid, this bile salt constituted approximately 60% of all bile salts. The patients receiving combined treatment had reduced cholesterol synthesis, as reflected by a 45% reduction in serum lathosterol. The activity and the mRNA levels of cholesterol 7 alpha-hydroxylase and the mRNA levels for the low density lipoprotein-receptor were not significantly affected. CONCLUSIONS: Pravastatin does not further reduce the cholesterol saturation of bile in gallstone patients treated with ursodeoxycholic acid, although hepatic cholesterol synthesis is inhibited. The study supports the important concept that de novo synthesized cholesterol is not particularly important for biliary cholesterol secretion in humans.     

腹腔镜胆囊切除术胆管损伤的原因及处理

目的探讨腹腔镜胆囊切除术（LC）中胆管损伤（Bile duct injury，BDI）原因及处理方法。方法1996年至2007年2854例腹腔镜胆囊切除术（LC）中11例胆管损伤的原因，损伤的部位进行探讨。其中解剖病理因素7例，操作因素4例。损伤部位：胆总管6例，肝总管4例，右肝管1例。结果9例经中转开腹8例行胆管修补加T管支撑。1例行胆总管空肠吻合术加支撑。LC术后因出现胆汁性腹膜炎再手术发现胆管损伤2例，其中胆总管及肝总管损伤各1例。1例行胆管修补加T管支撑。1例行胆管端端吻合术加T管支撑。结论掌握好中转开腹时机是避免LC胆管损伤的重要环节。     

Managing concomitant gallbladder stones and common bile duct stones in the laparoscopic era: a systematic review

Background: There is still no consensus on the ideal management of common bile duct (CBD) stones. This article aims to review the management of concomitant gallbladder stones and CBD stones in the laparoscopic era. Method: A PubMed database search was performed to identify MEDLINE articles from 1986 to 2010 using the key terms “common bile duct stones,”“cholecystectomy,”“bile duct exploration,”“ERCP” (endoscopic retrograde cholangiography), and “endoscopic sphincterotomy.” Results: There were five randomized comparative trials (RCT) comparing sequential preoperative ERCP and laparoscopic cholecystectomy (LC) to laparoscopic common bile duct exploration (LCBDE). Two RCTs showed similar stone clearance rates and shorter hospital stays in the LCBDE group, while three RCTs showed similar stone clearance rates and hospital stays in sequential preoperative ERCP, LC and LCBDE groups. There were two RCTs comparing LCBDE to sequential LC and postoperative ERCP. One showed similar stone clearance rate and shorter hospital stay in LCBDE group, while the other showed similar stone clearance rate and hospital stay. There were three RCTs comparing sequential preoperative ERCP and LC against LC with intraoperative ERCP. All three studies showed similar stone clearance rates and shorter hospital stays in the intraoperative ERCP group. There was only one RCT comparing sequential preoperative ERCP and LC against sequential LC and postoperative ERCP. This showed a similar stone clearance rate and shorter hospital stay in the postoperative ERCP group. Conclusion: Different management approaches of concomitant gallbladder stones and CBD stones were equivalent in efficacy. However, one‐stage management had the advantage of providing a shorter hospital stay.